Brake mechanism



Sept. l5, 1953 R. L.. BRowNlNG BRAKE MECHANISM 2 Sheets-Sheet 1 Original Filed Oct. 6, 1945 SPf 15, 1953 R. L. BRowNlNG 652,132

' BRAKE MECHANISM Original Filed Oct. 6, 1943 2 Sheets-Sheet 2 1271/621701" RICHARD LBROWNIING.

Patented Sept. 15, 1953 BRAKE MECHANISM Richard L. Browning, Euclid, Ohio, assignor to Victor R. Browning & Company, Incorporated, Willoughby, Ohio, a corporation of Ohio Original application October 6, 1943, Serial No. 505,089. Divided and this application February 18, 1949, Serial No. 77,201

Claims.

This invention relates to a braking mechanism. In its preferred form it comprises a brake held inactive by means associated with the driving mechanism of the apparatus to which the brake is attached and rendered operative to retard or stop such apparatus upon the shutting down of the driving mechanism. The invention is peculiarly adapted for use in connection with a hoist mechanism driven by an electric motor wherein a magnetic unit in circuit with the motor normally holds the brake inactive, but Which serves to release the brake to operative position through spring action or the like when the motor switch is moved to stop the motor and deenergize the magnetic unit. The invention includes precision adjustment of the brake-shoe spacing and plane of operation, as well as the limit of free movement of the brake-shoes, and provides broad bearing surfaces for the pivot elements to insure long service life.

The principal object of the present invention is to simplify and improve the construction of braking mechanism for use on various types of apparatus, including cranes and hoisting apparatus.

Another object of the invention is to provide an improved braking mechanism consisting of few parts particularly adapted for easy and ready assembly and installation of the brake shoes, adjustment thereof and readily accessible for inspection or replacement.

Another object of the invention is to provide an improved mounting for a brake shoe of simplified construction and readily adjusted to position the brake shoe in predetermined relation to its brake drum or Wheel from time to time due to Wear of the shoe lining whereby non-uniform wear of the lining is eliminated.

Another object of the invention is to provide an improved mounting for a brake shoe capable 0f adjustment to relate the shoe to its drum or Wheel independently of the brake shoe operating mechanism.

Another object of theinvention is to provide a pair of brake levers carrying brake-shoes on eccentric elements adapted for ready adjustment and supporting said brake-shoes on broad bearing elements thereby, reducing the wear upon the associated parts.

Other objects of the invention Will be apparent to those skilled in the art to which my invention relates from the following description taken in connection with the accompanying drawings, wherein Fig. l is a side elevation of a brake apparatus embodying the principles of the invention;

Fig. la is a fragmentary section on the line Ia-Ia of Figs. 1 and 4;

Fig. 2 is an end view of the apparatus shown in Fig. 1 as seen from the right-hand side Fig. 3 is a fragmentary diagrammatic plan View of the apparatus with brake-shoes and brake drum removed; and

Fig. s is a fragmentary sectional View of the brake-shoe adjusting mechanism.

As clearly shown in the drawings, the automatic brake apparatus may be embodied in a Skeletcrdzed structure i comprising side frames formed of pairs of angle bars welded to form rectangular side bars 2, 3, having a plurality of standards with spacing members 5. A removable frame section iii, bolted to the main frame by pairs of bolts Il, supports a magnet housing having therewithin a magnet coil "i, the latter being preferably connected with the motor (not shown) with which is associated the brake drum 3. The units may be variously connected but preferably the motor is in series with the magnet and the magnet when energized releases the brake-shoes from the drum, as will be presently described.

The brake-shoes II, I2, are each carried on pivoted frame members I 3, I4, of bell-crank shape supported between pairs of side plates or standards i5, I t, and i7, It, respectively, Welded at spaced points to the side frame bars 2, 3, and preferably having gusset plates I9. The free ends of the bell-crank frame members are turned tov/ard each other and carry rollers 2|, 22, respectively, in closely spaced relation centrally between the side bars 2, 3. The pivots 23, 24, for the respective bell-crank frames are adjacent the lower portions of their upright sections and comprise pivot pins engaged through apertures in the upper portions of the pairs of standards I5, I6, and El, is, respectively. The pivot pins 23, 24, are provided with terminal bars 25, 26, respectively, at one end and the bars in turn carry locking bolts 2l, 28, respectively, engageable in suitable apertures on the adjacent standards referred to, respectively. Suitable hardened bushings 29 are frictionally engaged in the bell-crank frames and are engaged over the hardened pins to reduce wear to a negligible amount. The angle sections of the bell crank frame members I3, It, are connected to each other by a light spring 3d, having its ends engaged over studs 3|, 32, spaced inwardly of and a slight distance from the rollers 2 i, 2?., at a central position, on the adjacent ends of the members i3, I4. A similar spring may be used on each side of the members I3, It, for balanced action. At the upright ends of the bellcrank members I3, I 4, pivot pins 33, 3i, are provided having terminal bars 35, 36, respectively With locking bolts 3l, 38, respectively, engaging the frame members I3, I4. The pivot pins revolubly support cylindrical adjusting members 4I, i2, each having an oir-center or eccentric bore 43 through which the adjacent pin extends. Each adjusting member 4I, 42, is formed adjacent its opposite ends with radially disposed apertures 44 (see Fig. 2) adapted to receive a suitable tool, whereby the member may be adjusted about the adjacent pin. The brake-shoes I I, I2, are of conventional arcuate shape and have suitable friction linings 45, each secured to the body of the adjacent shoe by suitable fastening means, such as rivets 425. The rear side or wall of each brake shoe is enlarged centrally to form a boss 41 and provided with longitudinally extending ribs 41a at opposite sides of the boss. The boss 41 is formed with a transverse aperture 48 and the ribs 41a are formed with openings 41h alined with the aperture 48. The openings 41h and aperture 48 are of a size to receive the cylindrical adjusting member 4i or 42, above mentioned, for spacing the adjacent shoe from the brake drum 8. In this arrangement, the opposite end portions of the adjacent eccentric member are rotatably mounted in the openings 41h, whereby it may be adjusted about the axis of the adjacent pivot pin, and thus support the shoe in relation to the drum 8 for eifective braking engagement therewith. By preference, each eccentric member 4I, 42, is adjustably fixed to the walls of the adjacent aperture 48. For this purpose, the transverse aperture 43 may be in the form of a split socket, whereby, by means of a bolt 49, the adjacent eccentric member may be secured to the boss 41 after it is adjusted at the proper angle to space the brake-shoe a predetermined distance from the brake drum 8. As shown in Figs. la and 2, the eccentric member 4I extends outwardly beyond the ribs 41a, so as to provide for an adjustment of the shoe axially of the adjacent pivot pin and eccentric member, parallel to the axis of the drum 3, to insure alinement with the latter and compensate for end play of the shaft to which the drum s is keyed or otherwise secured. By loosening the bolt 49, the eccentric member may be adjusted as above set forth and/or the brakeshce adjusted axially thereof in operative relation to the drum 8. It will be thus noted that the lateral position of the brake-shoe on the drum as well as its spacing from the drum is adjusted preliminary to tightening the clamping bolt 49. The radial apertures 44 permit rotation of the eccentric members by means of a bar or similar instrument to a position or precise spacing of each brake-shoe from the surface of the brake drum. 5I indicates as an entirety means between each bell-crank member I3, I4, and the adjacent brake-shoe for preventing downward movement of the brake-shoe and thus allow the motor armature, where the brake is applied, to be removed or a replacement thereof made, without any change of adjustment of the brake-shoe. Accordingly, such repair or replacement may be expedited, so that in the case of an emergency condition, the great expense, which would otherwise result from a long tie up of the mechanism and stoppage of operations being carried out, is eliminated. The means 5I, as shown in Fig. l, consist of an extension or lug 5in. on one side and adjacent the lower end portion of each brake-shoe and an adjusting bolt 52, screw-threadedly engaged in an extension plate or nut 53 xedly mounted on the central portion of the adjacent bell-crank frame member, the outer end of the bolt being in engagement with the lug 5 Ia to limit the pivotal movement downwardly of the adjacent brake-shoe. Thus it will be observed that the adjusting screws 52 provide means of rotating the shoes I I and I2 about the pins 33, 34, thereby making possible the equalizing of clearance be- 4 tween brake wheel 8 and brake linings 4,5. The center of gravity of each brake-shoe II, I2, is

toward the brake wheel 8, thereby keeping the shoe in contact with the adjacent adjusting screw 52 (when brake-shoe is in released position) due to its own weight. Since each screw 52 moves axially by its rotation in the adjacent nut 53,

i which is a part of the adjacent frame member and makes contactwith the lug Ela, which is a part of the adjacent shoe, such axial movement causes shoe II to move about its supporting pin. In Fig. 4, I show a modified form of limiting means wherein a U-shaped plate terminal 54 is swivelled on the shoe and is used to limit upward as well as downward movement and vibration of the brake-shoe. The means for moving the brake-shoes toward and against the drum 8 is provided by an independent removable frame unit, having an armature frame BI carrying an armature 6U. The frame 6I is fulcrumed on the frame section I0 by means of a pivot pin 62 held by a set-screw $3 seated against a iiattened area 54 thereon. The lower end of the armature frame 6I is extended and projects through an opening formed in the frame member i3 below the pivot pin 23 therefor so as to terminate in a plane above the rollers 2 I, 22, as shown in Fig. 1. A hardened bushing 65 is frictionally engaged in the armature frame which, it will be noted, oscillates the slight distance necessary to apply or release braking pressure. The eXtreme lower end of the armature frame 6I supports a pressure roller 68 at a central position immediately above and in alinement with the rollers 2I, 22 (see Figs. 1 and 3), which are mounted in closely spaced relation on the respective free ends of the bellcrank frame members I3, I4, carrying the brakeshoes. The rollers 66, and 2I, 22, are all preferably ball-bearing units, mounted on parallelly related axes and are of substantial width. The roller t6 is preferably of approximately the diameter of the rollers 2I, 22, and traverses a path of movement in the plane of and between the rollers 2I, 22. Thus, while the independent bell-crank 5 frame unit, in the preferred form of construction,

is not positively connected with the brake-shoe operating members I3, I4, it has in effect a toggle action against said members increasing in effectiveness progressively with the amount of movement of the frame 6I and the degree of separation of the rollers 2I and 22. The means for controlling the armature frame 6I may vary with the structure to which it is applied, but in the apparatus illustrated and adapted for use in cranes and hoisting apparatus, it is moved to braking position by a compression spring 1I when the armature 60 is released by the magnet 1.

The armature frame 6I is provided at a central position with an upright channel bar 'I2 the upper end of which is formed with an aperture for one end portion of a rod 13, formed of nonmagnetic material and having a screw-threaded end section on which is mounted a nut 13a having a combined spring tensioning hand lever I4 and emergency brake release, the nut 13a engaging a washer 13b on the outer side of the bar 12. A compression spring 1I is coiled around the rod 13, and at one end abuts the inner side of the bar 12, whereas its opposite end abuts a nonmagnetic washer 16 seated against a pair of spring abutment nuts 11, 18 (also formed of nonmagnetic material) engaged on the screw-threaded rod 13. Under normal operation, the nut 13a is so positioned on the rod 13 that when the drum 8 is being drVeIl and brake-shoes I l, l2, are disengaged therefrom (see Fig. 1) as already set forth, the nut 13a and washer 13b are spaced from the channel bar l2, to permit rocking of the frame 9i about its fulcrum 52, under the influence of the spring ll, when the coil i is deenergized, and movement of the bar 12 a predetermined distance, whereby operation of the roller 65, through rollers 2|, 22, applies the brakeshoes to the drum il. The outer end of the rod i3 is screw-threadedly engaged in a terminal plate 'I9 on the armature housing 5, to which it is fastened by means of a terminal nut 80. The channel bar upright 'i2 is preferably welded to the armature 50.

The operation of the apparatus has been indicated in the description of the structural parts, but may be briefly summarized as relates to the form of construction illustrated as follows. When the switch is turned to energize the motor, the magnet 'i is also energized and the armature El! is attracted to the magnet. As the compression spring 'il is further compressed and the upright portion or bar 72 of the armature frame moves toward the magnet the lower end of the armature frame carrying the roller 65 is moved away from the rollers 2i, 22. The light tension spring 30, then turns the bell-crank members i3, M, carrying the brake-shoes I l, I2, away from the brake drum 8 and the apparatus operates freely until the motor is shut down. When the current is cut oif, the magnet will be de-energized and the compression spring il will force the armature frame away from the magnet, depressing the roller B and forcing the rollers 2i and 22 outwardly to operate the upper portions of the bell-crank members carrying the brake-shoes Il, l2, into pressure applying movement toward the brake drum. As will be observed the braking pressure is increased in effectiveness with the degree of movement of the roller S5 against the rollers 2|, 22. This also compensates for the reduction in pressure of the expansion spring in its movement toward a free-length position. The movement of the roller 65 is positive against the two rollers 2l, 22, and if the associated mechanism of either roller 2l or 22 fails, the full pressure of the roller 66 will be applied to the other roller of the pair and full braking pressure thus applied through a single shoe. This differs from units which become inoperative when one unit of the pair fails.

The apparatus provides a structure of great strength and of relatively light weight. Through the use of bell-crank members with roller terminals and with the pressure applying frame nested within the brake-shoe carrying members a very compact structure results without loss of leverage. The degree of movement of the parts, as well as the number of structural parts, is reduced to a minimum. This also facilitates the manufacture of the device and its assembly and maintenance. This is of particular importance in connection with the use of the apparatus on cranes and hoisting mechanism, where compactness and speedy dependable operation are essential.

While applicant has described one form of combination embodying the invention, it is not intended to restrict the invention to an electromagnetic brake operating mechanism, inasmuch as a mechanical or a uid operated mechanism may be used to advantage.

This application is a division of my application led October 6, 1943, Ser. No. 505,089, noW Letters Patent No. 2,491,359, dated December 20, 1949.

Other modes of applying the principle of my invention may be employed instead of those eX- plained, change being made as regards the structure and apparatus herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

What I claim is:

1. In a brake mechanism, the combination with a frame, spaced supports on said frame and a brake drum rotatably mounted on said frame between said supports, of levers disposed in the plane of said drum and each fulcrumed intermediate its ends on one of said supports, each of said levers terminating at one end in spaced arms having alined bearings, a brake shoe disposed between the arms of each lever in the plane of said drum and adapted to engage and disengage the latter, a boss on the rear side of each of said brake shoes intermediate its ends and formed with a through transverse opening, a device rotatably tting and extending through the opening in each of said bosses, and extensions on the opposite ends of each of said devices disposed eccentrically to the axis thereof and rotatably mounted in said adjacent bearings, the rotation of each said device serving to adjust the adjacent shoe relative to said drum.

2. A mechanism as claimed in claim 1 wherein one end of each of said devices is provided with elements adapted to be engaged by a tool to effect rotative adjustment thereof in said transverse opening.

3. In a braking mechanism, the combination with a frame, spaced supports thereon and a brake drum mounted on said frame between said supports, of levers disposed in the plane of said drum and each fulcrumed intermediate its opposite ends on one of said supports, each of said levers terminating at one end in spaced arms having alined bearings, a brake shoe disposed between the arms of each of said levers in the plane of said drum and adapted to engage and disengage the latter, a boss on the rear side of each of said brake shoes intermediate its opposite ends and formed with a through transverse opening, a pin mounted at its opposite ends in the bearings in the arms of each of said levers, an eccentric extending through and rotatably tting the opening in each of said bosses and formed with a through opening the walls of which engage and rotate on the adjacent pin, and elements provided on one end of each of said eccentrics for revolving the latter about the adjacent pin to adjust the adjacent brake shoe relative to said drum.

4. A mechanism as claimed in claim 1 wherein each of said bosses is slidable endwise of the adjacent device to adjust the adjacent shoe laterally relative to said drurn.

5. A mechanism as claimed in claim 1 wherein means are provided for securing each of said rotatable devices to the wall of the adjacent transverse opening.

RICHARD L. BROWNING.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,646,932 Rosenberg Oct. 25, 1927 1,672,314 Hall June 5, 1928 1,734,754 Thompson Nov. 5, 1929 2,285,134 Williams June 2, 1942 2,357,212 Magee Aug. 29, 1944 2,444,313 Rotenberger June 29, 1948 2,491,850 Browning Dec. 20, 1949 

